In recent years, the memory market has gradually shifted from being PC (personal computer) driven to being consumer device driven. Accordingly, memory with high density and speed, low power consumption, small form factor, and inexpensive data storage has been in high demand.
Memory can either be classified as volatile or non-volatile. Volatile memory is memory that loses its contents when the power is turned off. In contrast, non-volatile memory does not require a continuous power supply to retain information. As such, non-volatile memory devices are widely employed in computers, mobile communications terminals, memory cards, and the like. Many non-volatile memories use solid-state memory devices as memory elements. In some cases, nonvolatile memory devices have employed flash memory. In recent years, non-volatile memory devices designs have employed resistance random access memory (RRAM). A unit cell of RRAM usually includes a data storage element which has a variable resistive material layer. Generally, the resistance of the variable resistive layer can be changed with an electrical pulse to write data to the unit cell of RRAM.
Given the general desire to quickly store and retrieve ever-increasing amounts of digital information, designers and manufacturers of memory devices are continually striving to increase the memory cell density of storage media to store greater amounts of information in smaller areas. Accordingly, there is a need for improvements in memory design to decrease memory cell size and thus increase memory cell densities.